Re: [Qemu-devel] [PATCH 07/23] target-i386: convert cpuid features into properties

[Eduardo Habkost]

On Tue, Oct 02, 2012 at 05:38:45PM -0300, Eduardo Habkost wrote:
> (Now replying on the right thread, to keep the discussion in the right
> place. I don't know how I ended up replying to a pre-historic version of
> the patch, sorry.)
> 
> On Tue, Oct 02, 2012 at 05:36:59PM +0200, Igor Mammedov wrote:
> [...]
> > @@ -1938,6 +2043,12 @@ static void x86_cpu_initfn(Object *obj)
> >      object_property_add(obj, "tsc-frequency", "int",
> >                          x86_cpuid_get_tsc_freq,
> >                          x86_cpuid_set_tsc_freq, NULL, NULL, NULL);
> > +    x86_register_cpuid_properties(obj, feature_name);
> > +    x86_register_cpuid_properties(obj, ext_feature_name);
> > +    x86_register_cpuid_properties(obj, ext2_feature_name);
> > +    x86_register_cpuid_properties(obj, ext3_feature_name);
> > +    x86_register_cpuid_properties(obj, kvm_feature_name);
> > +    x86_register_cpuid_properties(obj, svm_feature_name);
> 
> Stupid question about qdev:
> 
> - qdev_prop_set_globals() is called from device_initfn()
> - device_initfn() is called before the child class instance_init()
>   function (x86_cpu_initfn())
> - So, qdev_prop_set_globals() gets called before the CPU class
>   properties are registered.
> 
> So this would defeat the whole point of all the work we're doing, that
> is to allow compatibility bits to be set as machine-type global
> properties. But I don't know what's the right solution here.
> 
> Should the qdev_prop_set_globals() call be moved to qdev_init() instead?
> Should the CPU properties be registered somewhere else?

Replying to myself: it wouldn't make sense to call it on qdev_init() as
it would overwrite properties set between the calls to object_new() and
qdev_init().

But I still don't see what would be the proper way to solve this. I
don't see any mechanism that would allow us to ensure the
object_property_add() calls are made before qdev_prop_set_globals() is
called.

-- 
Eduardo